/**
 * 现金额转大写
 * @param  {Number} n
 * @return {String}
 */
function digitUppercase(n) {
    var fraction = ['角', '分'];
    var digit = ['零', '壹', '贰', '叁', '肆', '伍', '陆', '柒', '捌', '玖'];
    var unit = [['元', '万', '亿'], ['', '拾', '佰', '仟'] ];
    var head = n < 0 ? '欠' : '';
    n = Math .abs(n);
    var s = '';
    for (var i = 0; i < fraction.length; i++) {
    	s += (digit[Math .floor(n * 10 * Math .pow(10, i)) % 10 ] + fraction[i]).replace(/零./, '');
    }
    s = s || '整';
    n = Math .floor(n);
    for (var i = 0; i < unit[0 ].length && n > 0; i++) {
        var p = '';
        for (var j = 0; j < unit[1 ].length && n > 0; j++) {
            p = digit[n % 10 ] + unit[1 ][j] + p;
        	n = Math .floor(n / 10 );
    	}
        s = p.replace(/(零.)*零$/, '').replace(/^$/, '零') + unit[0 ][i] + s;
    }
    return head + s.replace(/(零.)*零元/, '元')
    		.replace(/(零.)+/g, '零')
    		.replace(/^整$/, '零元整');
}